package cn.arnold.offer.qunar;

import java.util.Scanner;

public class Main {
    static int N = 4;
    static int M = 2;
    static int[] a = new int[N];
    static int[] b = new int[M];
    static int count = 0;

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int m = scanner.nextInt();
        int n = scanner.nextInt();
        N = m;
        M = n;
        a = new int[N];
        b = new int[M];
        for (int i = 0; i < n; i++) {
            a[i] = i + 1;
        }
        System.out.println(C(N, M));
    }

    public static int C(int m, int n) {
        int i, j;
        for (i = n; i <= m; i++) {
            b[n - 1] = i - 1;
            if (n > 1) {
                C(i - 1, n - 1);
            } else {
                for (j = 0; j <= M - 1; j++) {

                }
                count++;
            }
        }
        return count;
    }
}
